Studies on the reproductive physiology of the common beans, Phaseolus vulgaris L. (VII)

The effects of temperature on the function of pollen and pistil

Abstract

In order to clarify the effects of temperature on the function of pollen and pistil in the common bean, experiments were carried out, using a dwarf variety “Masterpiece”. The results obtained are summarized as follows:
1) The fertilizing ability of pistil occurred from 3 days before anthesis. Set percentage increased gradually toward the day just before anthesis.
2) By the method of cutting style after pollination, the authors studied the velocity of elongation of pollen tube. In the case of cutting after 1 hour, a few pods were secured, and the later the cutting time, the higher the set percentage. But the increase in set percentage was very small when the temperature was high.
3) The potted plants were placed under the constant temperatures between 10°C and 45°C for 4 hours, after pollination and then the styles were cut off. No pods were secured under 10°C and 45°C, and there were observed only very poor set under 30_??_40°C, while good results in the set of pods were obtained under 15_??_25°C.
4) To study the effect of alternating tempera-tures on set percentage, the 2 plots were set, one from 25°C to 35°C (each for 2. 5 hours) after pollination and the other from 35°C to 25°C. The set percentage of the former was worse than that of the latter.
5) The potted plants were placed under constant temperatures between 10°C and 45°C for 4 hours, and then were pollinated. Under 10°C and 45°C, no pods were secured. But under the range of 15_??_40°C, the set percentages were pretty high and there were no significant differences among them. It seems, therefore, that the pistil adapts oneself to wider range of temperature than pollen.